sunxi: mmc: Fix T113-s3 MMC clock divider

sunxi: mmc: Fix T113-s3 MMC clock divider

On the Allwinner D1/R528/T113-s3 SoCs the MMC clock source selected by
mux value 1 is PLL_PERIPH0(1x), not (2x), as in the other SoCs.
But we have still the hidden divisor of 2 in the MMC mod clock, so
need to explicitly compensate for that on those SoCs.

This leads to the actually programmed clock rate to be double compared
to before, which increases the MMC performance on those SoCs.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reported-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>